粘包，Telnet,SSH,Wireshark

一，粘包

原因：tcp为流式套接字，数据与数据间没有边界，导致多次数据粘到一起。

解决：

1.规定一些数据间的间隔符，"\aa","\r\n";

2.可以指定要发送对象的数据长度。

3.自己将数据打包。

1.上传接收粘连

1.用户端

#include <head.h>


int connect_server(const char *ip,const char *port)
{
	int fd = socket(AF_INET,SOCK_STREAM,0);
	if (fd < 0)
		handle_error_ret("socket fail");

	struct sockaddr_in seraddr;
	memset(&seraddr,0,sizeof(seraddr));

	seraddr.sin_family = AF_INET;
	seraddr.sin_addr.s_addr = inet_addr(ip);
	seraddr.sin_port = htons(atoi(port));//"50000"  

	if (connect(fd,(const struct sockaddr *)&seraddr,sizeof(seraddr)) < 0)
		handle_error_ret("connect_server fail");

	return fd;
}



//./cli 127.0.0.1 50000 filename 
int main(int argc, const char *argv[])
{
	if (argc != 4)
	{
		printf("usage: %s <ip> <port> <filename>\n",argv[0]);
		return -1;
	}

	int fd = connect_server(argv[1],argv[2]);
	if (fd < 0)
		return -1;
	
	int fd_s = open(argv[3],O_RDONLY);
	if (fd_s < 0)
		handle_error_ret("open fail");

	write(fd,argv[3],strlen(argv[3])+1);
//	write(fd,argv[3],strlen(argv[3]));

	char buf[100] = {0};
	int ret = 0;

	while (1)
	{
		ret = read(fd_s,buf,sizeof(buf));
		if (ret == 0)
			break;
		write(fd,buf,ret);
	}

	close(fd_s);
	close(fd);

	return 0;
}

2.服务器

#include <head.h>


int init_server(const char *ip,const char *port)
{
	int fd = socket(AF_INET,SOCK_STREAM,0);
	if (fd < 0)
		handle_error_ret("socket fail");

	struct sockaddr_in seraddr;
	memset(&seraddr,0,sizeof(seraddr));

	seraddr.sin_family = AF_INET;
	seraddr.sin_addr.s_addr = inet_addr(ip);
	seraddr.sin_port = htons(atoi(port));//"50000"  

	if (bind(fd,(const struct sockaddr*)&seraddr,sizeof(seraddr)) < 0)
		handle_error_ret("bind fail");


	if (listen(fd,5) < 0)
	   handle_error_ret("listen fail");


	return fd;

}

//./ser 127.0.0.1 50000 
int main(int argc, const char *argv[])
{
    int ret = 0;
	if (argc != 3)
	{
		printf("Usage: %s <ip> <port>\n",argv[0]);
		return -1;
	}

	int listenfd = init_server(argv[1],argv[2]);

	if (listenfd < 0)
		return -1;


	int connfd = 0;

	if ((connfd = accept(listenfd,NULL,NULL)) < 0)
		handle_error_ret("accept fail");


	//读文件名 
	char buf[100] = {0};
	ret = read(connfd,buf,sizeof(buf));
	printf("ret = %d buf = %s\n",ret, buf);

	int fd_d = open(buf,O_WRONLY|O_CREAT|O_TRUNC,0666);
	if (fd_d < 0)
		handle_error_ret("open fail");

	while (1)
	{
		ret = read(connfd,buf,sizeof(buf));
		printf("ret = %d buf1 = %s \n",ret,buf);
		if (ret == 0)
		   break;
		write(fd_d,buf,ret);
	}

	close(fd_d);
	close(connfd);

	return 0;
}

3.注意

服务器和客户端不能写在同级别文件夹中

2.解决粘连

1.客户端

#include <head.h>


int connect_server(const char *ip,const char *port)
{
	int fd = socket(AF_INET,SOCK_STREAM,0);
	if (fd < 0)
		handle_error_ret("socket fail");

	struct sockaddr_in seraddr;
	memset(&seraddr,0,sizeof(seraddr));

	seraddr.sin_family = AF_INET;
	seraddr.sin_addr.s_addr = inet_addr(ip);
	seraddr.sin_port = htons(atoi(port));//"50000"  

	if (connect(fd,(const struct sockaddr *)&seraddr,sizeof(seraddr)) < 0)
		handle_error_ret("connect_server fail");

	return fd;
}



//./cli 127.0.0.1 50000 filename 
int main(int argc, const char *argv[])
{
	if (argc != 4)
	{
		printf("usage: %s <ip> <port> <filename>\n",argv[0]);
		return -1;
	}

	int fd = connect_server(argv[1],argv[2]);
	if (fd < 0)
		return -1;
	
	int fd_s = open(argv[3],O_RDONLY);
	if (fd_s < 0)
		handle_error_ret("open fail");

	//write(fd,argv[3],strlen(argv[3])+1);
	write(fd,argv[3],strlen(argv[3]));

	//方式1 
	//sleep(1);


	//方式2 
	write(fd,"\r\n",2);


	char buf[100] = {0};
	int ret = 0;

	while (1)
	{
		ret = read(fd_s,buf,sizeof(buf));
		if (ret == 0)
			break;
		write(fd,buf,ret);
	}

	close(fd_s);
	close(fd);

	return 0;
}

2.服务器

#include <head.h>


int init_server(const char *ip,const char *port)
{
	int fd = socket(AF_INET,SOCK_STREAM,0);
	if (fd < 0)
		handle_error_ret("socket fail");

	struct sockaddr_in seraddr;
	memset(&seraddr,0,sizeof(seraddr));

	seraddr.sin_family = AF_INET;
	seraddr.sin_addr.s_addr = inet_addr(ip);
	seraddr.sin_port = htons(atoi(port));//"50000"  

	if (bind(fd,(const struct sockaddr*)&seraddr,sizeof(seraddr)) < 0)
		handle_error_ret("bind fail");


	if (listen(fd,5) < 0)
	   handle_error_ret("listen fail");


	return fd;

}

//./ser 127.0.0.1 50000 
int main(int argc, const char *argv[])
{
    int ret = 0;
	if (argc != 3)
	{
		printf("Usage: %s <ip> <port>\n",argv[0]);
		return -1;
	}

	int listenfd = init_server(argv[1],argv[2]);

	if (listenfd < 0)
		return -1;


	int connfd = 0;

	if ((connfd = accept(listenfd,NULL,NULL)) < 0)
		handle_error_ret("accept fail");


	//读文件名 
	char buf[100] = {0};

	FILE *fp = fdopen(connfd,"r");
	if (fp == NULL)
		handle_error_ret("fdopen fail");


	fgets(buf,sizeof(buf),fp);  //buf => 1.txt\r\n
	buf[strlen(buf)-2] = '\0';

//	ret = read(connfd,buf,sizeof(buf));
//	printf("ret = %d buf = %s\n",ret, buf);

	printf("buf = %s\n",buf);
	int fd_d = open(buf,O_WRONLY|O_CREAT|O_TRUNC,0666);
	if (fd_d < 0)
		handle_error_ret("open fail");

	while (1)
	{
		//ret = read(connfd,buf,sizeof(buf));
		ret = fread(buf,1,sizeof(buf),fp);
		printf("ret = %d buf1 = %s \n",ret,buf);
		if (ret == 0)
		   break;
		write(fd_d,buf,ret);
	}

	close(fd_d);
	close(connfd);

	return 0;
}

3.recv send函数（仅用于TCP中）

1.recv 类似于read函数

用法

比read函数多一个参数，仅用于TCP中

2.send 类似于write函数

send recv函数最后一个参数即允许非阻塞操作。

二，telnet,SSH,wireshark

1.telent

1.在windows中

telent可以在windows上用cmd创建一个linux，需要在linux中用ifconfig查看ip地址即可

linux IP为 192.168.11.128

2.第三方软件

以他实例

选择Telnet,输入IP

2.SSH

功能与telnet类似，只是传输过程加密

3.wireshark 抓包工具 抓取网络上数据

1.抓取telnet

输入指令打开

红色输入蓝色输出

2.抓取SSH

加密了

三次招手与四次挥手

3.wireshark中的命令